Trastuzumab is a cancer drug. It is normally used to treat a type of breast cancer called HER2 breast cancer. It can also be used to treat certain cancers of the stomach or throat (esophagus) that have spread.

Trastuzumab only works when the cancer cells have high levels of a protein called human epidermal growth factor receptor 2 (HER2). You will first have tests done to see if trastuzumab is suitable for you. It can also be used to treat other types of cancer as part of a research trial.

WHAT IS TRASTUZUMAB AND HOW DOES IT WORK?

Trastuzumab is part of a group of cancer drugs known as monoclonal antibodies. Monoclonal antibodies are sometimes called targeted therapies because they are oriented to specific proteins (receptors) located on the surface of cells.

Some types of cancer have too much of a protein called human epidermal growth factor receptor 2 (HER2) on the surface of their cells. These are known as HER2-positive cancers. The additional HER2 receptors stimulate the cancer cells to divide and grow. Trastuzumab latches on to the HER2 protein and blocks the receptor. This prevents the cells from dividing and growing.

There are different tests to measure levels of HER2 in cancer cells. These tests are performed using tissue taken during a biopsy or surgery to remove the cancer.

WHEN IS TRASTUZUMAB USED?

Breast cancer

Trastuzumab is a standard treatment for people with HER2-positive breast cancer. It is given at the same time as chemotherapy or after to reduce the risk of the cancer coming back. Trastuzumab can also be used to treat breast cancer that has returned or has spread to other parts of the body (secondary breast cancer). In this situation, it is given either on its own or in combination with chemotherapy and/or hormonal therapy.

Stomach and esophageal cancer

Trastuzumab can be used to treat certain people with advanced HER2-positive cancer of the esophagus where it joins the stomach. In this situation, trastuzumab is given in combination with chemotherapy.

HOW IS TRASTUZUMAB ADMINISTERED?

You can receive trastuzumab as a drip into a vein (intravenous infusion) or as an injection under the skin (subcutaneous). It can usually be given in the chemotherapy day unit.

You usually have trastuzumab every three month or once a week. If you have early-stage breast cancer, you will have trastuzumab over one year. If the cancer is advanced or has spread, you usually have trastuzumab for as long as it is controlling the cancer.

As a drip

Nurses give you the first dose (infusion) little by little, normally over a period of more than an hour and a half. You will stay in the hospital for a couple of hours after so you can be monitored for any reactions. If you don't have any problems with the first treatment, you can have the following infusions over 30 to 90 minutes and return home and hour after then.

As an injection under the skin

A nurse will give you an injection in your thigh. This only takes a few minutes. The site of the injection alternates between the left and right thigh. After the first injection, you will be monitored for a few hours to make sure that you don't develop a reaction. But after subsequent injections you will be monitored for a much shorter time.

POSSIBLE SIDE EFFECTS OF TRASTUZUMAB

Each person's reaction to cancer treatment is different: while some people develop very few side effects, others may experience more. The side effects described below will not affect everyone who is treated with the drug. We have outlined only the most common.

If you notice you develop any side effects that are not listed here, talk to your doctor or specialist nurse.

Side effects during treatment

The following side effects can happen during treatment with trastuzumab or a few hours after. They occur more frequently with the first dose and are much less likely to happen in subsequent doses.

ALLERGIC REACTION

Nurses will watch you closely to detect signs of this both during and after your treatment. The signs may include a skin rash, itchiness, wheezing, difficulty breathing, and breathlessness. Tell your nurse immediately if you have any of these symptoms. You can receive drugs called antihistamines before the infusion to reduce the likelihood of an allergic reaction. If you have an allergic reaction, the nurses will treat it quickly.

If you develop any of these signs or feel unwell after you get home, get in touch with your hospital immediately for advice.

FLU-LIKE SYMPTOMS

These can include headache, fever and chills, nausea, or vomiting. These symptoms can be controlled or reduced with drugs prescribed for you by your doctor. They tend to get better a few hours after trastuzumab is administered.

COMMON SIDE EFFECTS AFTER TREATMENT

HEADACHES

Let your doctor or nurse know if you have a headache. They can give you painkillers to help.

NAUSEA

Dizziness is normally mild, though your doctor can prescribe medication to reduce your nausea or vomiting.

LOSS OF APPETITE AND CHANGES IN TASTE

Try to eat frequent small meals. If your appetite doesn't get better, let your nurse or dietitian know. They can give you advice on getting more calories and proteins into your diet. Sucking on candy can sometimes help bitter or metallic tastes go away. Your nurse can give you further advice on this.

ABDOMINAL PAIN OR INDIGESTION

Tell your doctor or nurse if you have abdominal pain or indigestion. They can prescribe drugs to help reduce these side effects

DIARRHEA OR CONSTIPATION

Normally, this can be easily controlled with drugs, so tell your doctor if your diarrhea is severe or ongoing. It's important to drink lots of fluids if you have diarrhea.

Drinking at least two liters of fluids each day will help with constipation. Try to eat more high-fiber foods such as fruit, vegetables, and whole-grain bread and get some light exercise.

TIREDNESS AND FEELING OF WEAKNESS

Feeling tired is a common side effect. Try to maintain a good rhythm and rest as much as you need. Help balance this with a bit of light exercise, such as short walks. If you feel drowsy, don't drive or operate heavy machinery.

ACHING OR PAIN IN THE JOINTS AND MUSCLES

You may have pain or stiffness in the joints, or sometimes in your muscles. Let your doctor or nurse know if this happens. They can prescribe painkillers and give you advice.

EYE SORENESS

Your eyes may tear up. They may sometimes hurt or become inflamed (conjunctivitis). Your doctor can prescribe eye drops if you need them.

RUNNY NOSE OR NOSE BLEEDS

Tell your doctor or nurse if you have any of these side effects.

NUMBNESS OR TINGLING IN THE HANDS OR FEET

If this happens to you, it may also be hard for you to press buttons and it can make other tasks more uncomfortable. Usually, symptoms get better slowly after the treatment ends. Talk to your doctor if you are worried about this.

CHANGES IN YOUR NAILS OR SKIN

Tell your doctor if you develop any skin rashes. If your nails become brittle and break easily, wear gloves when washing the dishes or when handling detergent.

FEELINGS OF ANXIETY OR DIZZINESS OR DIFFICULTY SLEEPING

If you notice you have any of these side effects, tell your doctor or nurse.

INJECTION SITE

If you are taking trastuzumab as an injection under the skin, you may have discomfort, mild stinging, bruising, or reddening of the skin in the area of the injection. This is normally mild and temporary.

EFFECTS ON THE HEART

Trastuzumab can affect the way the heart functions. Your doctor will ask you if you have a history of heart problems, and you will have tests done to check the state of your heart and blood pressure before beginning treatment. Throughout the treatment and for a few years after the treatment is over, you will continue to have tests to determine your blood pressure and the state of your heart.

Tell your doctor immediately if, during or after your treatment, any of the following happens:

• chest pain or pressure in your chest
• breathlessness
• coughing
• changes to your heartbeat
• swelling in your arms or legs (caused by a build up of fluid).

These symptoms may be caused by other conditions, though it important to have them looked at by a doctor. If you have heart problems, they can be treated with pills.

INFECTIONS

Trastuzumab can reduce your number of white blood cells, which help fight off infection. This is more likely if you are receiving chemotherapy at the same time. This may make you more susceptible to infection.

Contact your hospital immediately if any of the following happens:

• your temperature goes above 38 ° C
• you suddenly feel unwell, even if your temperature is normal
• you have symptoms of infection, which may include sore throat, coughing, diarrhea, or the need to urinate frequently.

EFFECTS ON THE LUNGS

Always let your doctor know if you have wheezing, coughing, fever, or if you are out of breath. You should also get in touch with them if there is any existing problem with breathing. If necessary, tests can be done to check your lungs.

MORE INFORMATION ABOUT TRASTUZUMAB

OTHER MEDICINES

Some drugs, including those bought over the counter in a store or pharmacy, may be harmful to you while you are taking trastuzumab. Tell your doctor if you are taking any medicines, including over-the-counter drugs, complementary therapies, and herbal remedies.

CONTRACEPTION

Your doctor will advise you not to become pregnant or have children during the treatment. This is because the drugs can harm developing babies. It is important to use effective methods of contraception during chemotherapy and for up to seven months after the treatment ends. You can talk to your doctor or nurse about this.

BREASTFEEDING

There is a potential risk that trastuzumab may be present in breast milk, and therefore women are recommended not to breast feed during the treatment and for a few months afterward.

FERTILITY

The effects that trastuzumab can have on fertility are unknown. If this worries you, you can talk to your doctor or nurse before beginning treatment.

MEDICAL AND DENTAL TREATMENT

If you have to go to the hospital for whatever reason other than cancer, always tell the doctors and nurses that you are having trastuzumab.

Talk to your cancer doctor or nurse if you think you need dental treatment. Always let your dentist know that you are having trastuzumab.